A marginal improvement on last year’s “Twilight,” “New Moon” is a bit like being locked in a room for two hours with a very moody teenager.

The people most likely to appreciate the experience are other moody teens ... and moms who remember what it was like to be a moody teen.

I’ll admit up front that I’m not the ideal demographic for Stephenie Meyer’s tale of courtly love among the bloodsuckers. This movie isn’t going to change that.

In the hands of new director Chris Weitz, “Moon” is slicker than the original film. Clearly there was a bit more budget — the vampire Edward’s sparkly skin actually looks cool instead of cheesy this time around, and the film concludes with a sequence in a beautiful Italian country town.

But I’m sorry — I found the dilemma of our heroine Bella (Kristen Stewart) to have all the punch of a middling made-for-TV movie.

The first 30 minutes of “New Moon” finds Bella and Edward (Robert Pattinson) in an ever-deepening love affair. It’s not sexual — the only person in this movie who even thinks about sex is a grungy biker who tries to pick up Bella. No, it’s a union of soul mates.

But Edward fears that his presence is endangering Bella, and so he bids a final farewell. He and the entire Cullen clan of vampires pull up roots and vanish.

Bella goes into a funk. Anyone who has had a high schooler in the throes of romantic angst knows what a joy that is.

Thank heaven for Jacob (Taylor Lautner), her Quileute Indian friend. Lautner lacks Pattinson’s screen charisma and acting chops (he’s not helped any by the cheap wig he wears for half the movie), but he’s sweet and sincere.

Despite Jacob’s obvious crush on her, Bella still pines for Edward. When she learns that he has gone to Italy to beg the vampire high council to put him out of his misery, our girl jets to Europe to save the day.

Perhaps what bugs me most about the “Twilight” movies is that they don’t give Stewart a chance to stretch. In other films (“Adventureland,” “The Cake Eaters”), this young actress has suggested a depth and breadth barely tapped here.

Also problematic is the film’s desultory pacing. There’s little dramatic tension and, despite the fact that Bella is being stalked by the vengeful vampire Victoria (Rachelle Lefevre), not much sense of danger. (Lefevre will be replaced by Bryce Dallas Howard in the third installment, “Eclipse,” due out June 30.)

None of this is likely to deter the books’ fans from partaking of this cinematic rendering. They’ll come determined to swoon, and swoon they will — especially because the young male cast members are shirtless much of the time. The rest of us will be left scratching our heads and wondering what all the fuss is about.